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Ziegeler S.B.,Engility Corporation
Proceedings of ISAV 2016: 2nd Workshop on In Situ Infrastructures for Enabling Extreme-Scale Analysis and Visualization - Held in conjunction with SC 2016: The International Conference for High Performance Computing, Networking, Storage and Analysis | Year: 2016

In situ visualization promises to offer one solution to the problem of stagnant I/O bandwidths relative to computing capacity. Yet, it has drawbacks, including a lack of explorable results. This can be addressed by producing derived or extracted results instead of just images. However, the I/O for these results is not guaranteed to be sufficiently scalable if not designed properly. We present an I/O mini app that measures derived quantity I/O performance. It produces isosurfaces with a data generation function allowing fine control of the volume, load imbalance, and other aspects of the isosurface geometry output data. We also provide ongoing results of scalability benchmarks with various output methodologies. © 2016 IEEE.

Smith R.,Engility Corporation
Proceedings of PyHPC 2016: 6th Workshop on Python for High-Performance and Scientific Computing - Held in conjunction with SC16: The International Conference for High Performance Computing, Networking, Storage and Analysis | Year: 2016

Python is an interpreted language that has become more commonly used within HPC applications. Python benefits from the ability to write extension modules in C, which can further use optimized libraries that have been written in other compiled languages. For HPC users, two of the most common extensions are NumPy and mpi4py. It is possible to write a full computational kernel in a compiled language and then build that kernel into an extension module. However, this process requires not only the kernel be written in the compiled language, but also the interface between the kernel and Python be implemented. If possible, it would be preferable to achieve similar performance by writing the code directly in Python using readily available performant modules. In this work the performance differences between compiled codes and codes written using Python3 and commonly available modules, most notably NumPy and mpi4py, are investigated. Additionally, the performance of an open source Python stack is compared to the recently announced Intel Python3 distribution. © 2016 IEEE.

Byrd K.K.,Centers for Disease Control and Prevention | Furtado M.,Engility Corporation | Bush T.,Centers for Disease Control and Prevention | Gardner L.,Centers for Disease Control and Prevention
AIDS Care - Psychological and Socio-Medical Aspects of AIDS/HIV | Year: 2015

We used the US-based MarketScan® Medicaid Multi-state Databases to determine the un-weighted proportion of publically insured persons with HIV that were retained, continued, and re-engaged in care. Persons were followed for up to 84 months. Cox proportional hazards models were conducted to determine factors associated with gaps in care. Of the 6463 HIV cases identified in 2006, 61% were retained during the first 24 months, and 53% continued in care through 78 months. Between 8% and 30% experienced a gap in care, and 59% of persons who experienced a gap in care later reengaged in care. Persons with one or more Charlson co-morbidities (HR 0.72, 95% CI 0.64-0.81), ages 40-59 (0.79, 0.71-0.88), mental illness diagnosis (0.79, 0.72-0.87), hepatitis C co-infection (0.83, 0.75- 0.93), and female sex (0.86, 0.78-0.94) were less likely to experience a gap in care. Between 27% and 38% of those not retained in care continued to receive HIV-related laboratory services. This Medicaid claims database combines features of both clinic visits-based and surveillance lab-based surrogate measures to give a more complete picture of engagement in care than single-facility-based studies. © 2015, Routledge. All rights reserved.

Gaquin K.G.,Engility Corporation | Fields M.,U.S. Army
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2016

Smartphones have put powerful sensor arrays in nearly everyone's pockets. Fusing the data from these sensors it is possible to estimate the phone's current orientation. In this study we utilize a 3 axis gimbal to compare the performance of multiple orientation estimation algorithms. Controlling the position of the gimbal allows us to compare the known device orientation to the estimated orientation. Using this same method we determine where each algorithm's faults lie, and where they begin to break down. Then repeating these movements we are able to compare each algorithm to each other. © 2016 SPIE.

Liu J.L.,Center for Bio Molecular Science and Engineering | Dixit A.B.,University of Maryland, Baltimore | Robertson K.L.,Engility Corporation | Qiao E.,U.S. Navy | Black L.W.,University of Maryland, Baltimore
Proceedings of the National Academy of Sciences of the United States of America | Year: 2014

Packaging specific exogenous active proteins and DNAs together within a single viral-nanocontainer is challenging. The bacteriophage T4 capsid (100 × 70 nm) is well suited for this purpose, because it can hold a single long DNA or multiple short pieces of DNA up to 170 kb packed together with more than 1,000 protein molecules. Any linear DNA can be packaged in vitro into purified procapsids. The capsid-targeting sequence (CTS) directs virtually any protein into the procapsid. Procapsids are assembled with specific CTS-directed exogenous proteins that are encapsidated before the DNA. The capsid also can display on its surface high-affinity eukaryotic cell-binding peptides or proteins that are in fusion with small outer capsid and head outer capsid surface-decoration proteins that can be added in vivo or in vitro. In this study, we demonstrate that the site-specific recombinase cyclic recombination (Cre) targeted into the procapsid is enzymatically active within the procapsid and recircularizes linear plasmid DNA containing two terminal loxP recognition sites when packaged in vitro. mCherry expression driven by a cytomegalovirus promoter in the capsid containing Cre-circularized DNA is enhanced over linear DNA, as shown in recipient eukaryotic cells. The efficient and specific packaging into capsids and the unpackaging of both DNA and protein with release of the enzymatically altered protein-DNA complexes from the nanoparticles into cells have potential in numerous downstream drug and gene therapeutic applications. © 2014 PNAS.

Weber B.V.,U.S. Navy | Mosher D.,Engility Corporation | Ottinger P.F.,Engility Corporation
IEEE Transactions on Plasma Science | Year: 2014

This technical note reviews solutions for planar, relativistic space-charge-limited (SCL) flow both for the single species case with electrons and for bipolar flow with electrons and protons. In most cases, numerical integration or evaluation of special functions is needed to obtain values for these solutions. Here, fit functions for these solutions are derived so that they can be used to calculate 1-D SCL electron and proton current densities and the bipolar enhancement factor for any voltage, including the range transitioning from nonrelativistic to relativistic behavior (approximately 0.1-2 MV, γ =1.2-5 for electrons and 102-105 MV, γ =1.1-100 for protons). These fit functions reproduce the exact values to within a few percent, or with an error correction, to within a fraction of 1%. These functions should be useful for evaluating SCL current densities for a range of problems where relativistic effects are important and the 1-D approximation is applicable. © 2014 IEEE.

Idris H.,Engility Corporation
15th AIAA Aviation Technology, Integration, and Operations Conference | Year: 2015

Choke points in the national airspace system are resources for which demand exceeds capacity and hence generate delays that propagate through the system network. Under nominal conditions, airports, and more specifically runways, are the main choke points that generate most delays. A historical data analysis is conducted in order to compare and rank the major airports of the national airspace system. A number of metrics and techniques are used in order to isolate locally generated delays, which demonstrate choke point effects, from delays that are propagated from other airports. Namely, throughput saturation is used to quantify how severely demand exceeds capacity, delay relative to unimpeded travel time is used to quantify queuing effects, and passing is used to isolate the local queuing delays from delays due to control activity to conform to downstream constraints. Results provide insights on how the major airports compare in terms of generating delay locally versus manifesting propagated delay. © 2015, American Institute of Aeronautics and Astronautics Inc.

Ahlstrom U.,Technical Center | Jaggard E.,Engility Corporation
Transportation Research Part C: Emerging Technologies | Year: 2010

Adverse weather conditions are hazardous to flight and contribute to re-routes and delays. This has a negative impact on the National Airspace System (NAS) due to reduced capacity and increased cost. In today's air traffic control (ATC) system there is no automated weather information for air traffic management decision-support systems. There are also no automatic weather decision-support tools at the air traffic controller workstation. As a result, air traffic operators must integrate weather information and traffic information manually while making decisions. The vision in the Next Generation Air Transportation System (NextGen) includes new automation concepts with an integration of weather information and decision-making tools. Weather-sensitive traffic flow algorithms could automatically handle re-routes around weather affected areas; this would optimize the capacity during adverse conditions. In this paper, we outline a weather probe concept called automatic identification of risky weather objects in line of flight (AIRWOLF). The AIRWOLF operates in two steps: (a) derivation of polygons and weather objects from grid-based weather data and (b) subsequent identification of risky weather objects that conflict with an aircraft's line of flight. We discuss how the AIRWOLF concept could increase capacity and safety while reducing pilot and air traffic operator workload. This could translate to reduced weather-related delays and reduced operating costs in the future NAS.

Idris H.,Engility Corporation
27th Congress of the International Council of the Aeronautical Sciences 2010, ICAS 2010 | Year: 2010

The growth of air traffic demand is increasing the number of operations at major and secondary airports. As a result, the interdependencies between nearby airports are also increasing leading to the emergence of multi-airport systems (metroplexes). Often, these metroplexes constitute bottleneck capacities of the national air transportation network and hence a major cause of delay. The metroplex capacity limitations are caused by several inefficiencies. One such inefficiency is assigning the metroplex airspace among the competing airports based on procedures that segregate traffic by destination airport. These procedures limit the opportunity to share scare airspace resources dynamically between the airports and increase the mixing of slow and fast aircraft in single flows. This paper proposes assigning airspace and segregating traffic according to aircraft speed as opposed to the destination airport, resulting in sharing of airspace resources and potential throughput and flexibility gains. The proposed approach is analyzed, using simulation of hypothetical scenarios, in terms of airport throughput and aircraft trajectory flexibility.

Kuo V.H.,Engility Corporation
AIAA Guidance, Navigation, and Control Conference | Year: 2010

The non-cooperative aircraft increases the possibilities of midair collisions in the al-ready congested U.S. airspace. To counter this threat, a novel emergency evasive maneuver strategy is proposed, based on the reverse pure proportional navigation guidance, and requiring low levels of information concerning the non-cooperative aircraft. Using the time-varying nonlinear airborne equations of motion, a qualitative analysis of the relative trajectory between the own aircraft that performs the proposed emergency evasive maneuver and the non-cooperative aircraft that is assumed to collide with the own aircraft is presented. Sufficient conditions for the own aircraft to successfully avoid a collision with the non-cooperative aircraft are determined. Finally, simulation results are presented to demonstrate the effectiveness of the proposed emergency evasive maneuver against a pursing non-cooperative aircraft. Copyright © 2010 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved.

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